Ask exploding heads

A crossbow. I have exactly zero practical experience with any melee weapons, especially polearms, and I don't have any skill on a longbow, leaving the crossbow as not only the simplest weapon available, but also one I would be somewhat familiar with using due to experience on modern firearms. I would also stay away from the early firearms appearing at the time since a crossbow is more accurate and reliable, as well as more foolproof.

Regarding armor, I'd likely go with heavy cloth armor and chain mail since plate armor would be more restrictive than helpful considering I would stay away from the front.